Voltage

[psalcido@midwestfab.com]

I recently purchased a machine from the UK and did not realize the voltage used there is 415vac at 50HZ. We are in California using 480vac at 60Hz. The motors and transfomers are rated at 420vac. Would running the machines at 480vac be asking to much from the machine and should I use a step down transformer?

 

[zog]

I recently purchased a machine from the UK and did not realize the voltage used there is 415vac at 50HZ. We are in California using 480vac at 60Hz. The motors and transfomers are rated at 420vac. Would running the machines at 480vac be asking to much from the machine and should I use a step down transformer?

It is not so much the voltage that will give you problems as the frequency.

 

[chris1971]

I recently purchased a machine from the UK and did not realize the voltage used there is 415vac at 50HZ. We are in California using 480vac at 60Hz. The motors and transfomers are rated at 420vac. Would running the machines at 480vac be asking to much from the machine and should I use a step down transformer?[/QUOTE

IMO, I would look at getting a step down transformer.

 

[jim dungar]

Motors care about V/HZ. Both Europe and North America run at a nominal 8V/Hz. Changing your voltage with a transformer may be more of a problem than leaving things as they are.

As Zog pointed out, your bigger problem is probably the fact that your motors will want to run faster than the designer may have intended.

You may want to look at a VFD to feed your motors, although you may need to separate the control system on a transformer. Frequency sensitive equipment in the control system may need to replaced.

 

[weressl]

Motors care about V/HZ. Both Europe and North America run at a nominal 8V/Hz. Changing your voltage with a transformer may be more of a problem than leaving things as they are.

As Zog pointed out, your bigger problem is probably the fact that your motors will want to run faster than the designer may have intended.

You may want to look at a VFD to feed your motors, although you may need to separate the control system on a transformer. Frequency sensitive equipment in the control system may need to replaced.

Or you can run your entire machine from a ASD adjusted to the proper voltage and frequency.

 

[One-eyed Jack]

You need to make tap adjustments on your control transformer if there is one. The extra rpm on the motors can be a real concern. Had a 125 hp motor on a hydralic pump that was OEM for 50HZ. It was returned to the USA and hooked up as is. Motor was under fla from start-up just moving the fluid under NO PRESSURE. Went thru two owners and 200 thousand dollars worth of pumps before they listened to the EC and reduced the speed of the pumps.

 

[Besoeker]

Or you can run your entire machine from a ASD adjusted to the proper voltage and frequency.

If you went down that route, you might need a sinewave filter. Some equipment might not work too well with a PWM voltage waveform.

 

[Jraef]

You really need to carefully investigate what you have in your machine. If you have AC motors running without VFDs, then they will survive, but they will spin 20% faster which may be a problem. If they are centrifugal pumps, it will likely cause them to overload because load increases exponentially with speed. If they are AC motors with VFDs or DC motors with drives or servos or steppers, it may be completely irrelevant as most drives will be tolerant of a slight increase in line voltage without changing the output. Most modern power supply units (PSU) have wide voltage tolerances, but some cheaper ones do not, so you need to check that out.

Another issue to watch out for is that in the UK, the 415V is a Y feed, so it is 415Y230V and they sometimes use Phase to Neutral to get 230V single phase power for use by power supplies etc. or control system components like relays and contactors. In the US, you MIGHT have 480Y277 if your service is relatively new, but you also might have 480V delta, in which case all of the L-N operations would become dangerous. Even if you have 480Y277, that 277V might be out of tolerance for the control components, especially anything with coils.

In short, there are too many variables to just take a chance on a generalization. You need to investigate thoroughly.

 

[weressl]

If you went down that route, you might need a sinewave filter. Some equipment might not work too well with a PWM voltage waveform.

Absolutely.

 

[broadgage]

The official, or declared nominal voltage in the UK is now 230/400 volts, though the actual voltage supplied tends to be nearer 240/415, most of the time in most places.

400/415 volt, 50 cycle motors are normally fine on 480 volt 60 cycles since, as others point out, the volts/cycles ratio is the same.

However the greater speed of the motor might well overstress whatever the motor drives.

Contactor coils intended for 415 volt, 50 cycles are usually OK on 480 volt 60 cycles for the same reason.

But remember that UK contactors are normally 230/240 volt and wired between phase and neutral, they should be ok on 277 volt, 60 cycles, since the volts/cycles ratio is again the same.
But does your supply have a neutral ?

DC relays or contactors worked from an unregulated transformer/rectifier will be overstressed.

Detailed investigation will be required.

 

[chaterpilar]

I fully agree with Jraef,..

You have to make a list of items inside the machine as below..

a) Heaters No effect ( As long as the step down transfoormer is used)

b) Motors Will run 20% faster inspite of using step down transformer

c) Power supplies Have wide range of voltage supply and are normally 50/60 Hz

d) Sensors DC powered ( like proximity sensors, 4-20 ma transmitters), make sure the DC output is within the range.

e) Contactors Voltage/Freq ratio for the coil should remain same.


There is no generalisation, each component has to be engineered to work.

Cheers.

 

[Besoeker]

If they are centrifugal pumps, it will likely cause them to overload because load increases exponentially with speed.

Centrifugal pump loading (power) increases as the cube of the speed. Torque increases as the square of the speed.

Another issue to watch out for is that in the UK, the 415V is a Y feed, so it is 415Y230V and they sometimes use Phase to Neutral to get 230V single phase power for use by power supplies.

It's actually 400/230V nominally and has been so for about a decade now in order to harmonise with other EU countries (CENELEC Harmonization Document HD 472 S1:1988).
LV distribution is almost invariably a star or Y connection. Residential supplies, with very few exceptions, are 230V single-phase derived from the 400V LV distribution. All domestic appliances run from 230V.

In summary, we have just 400/230V. It's simple. I like simple.

Seasons greetings!
Mr B